Automatic clutch actuating mechanism



Oct. 22. 1940 J; H. K. MCCOLLUM ETAL 2,219,270

AUTOMATIC CLUTCH ACTUATING MECHANISM Original Filed Jan. 17, 1951 INVENTORS JAMES H. K. McCOLLUM HENRY J: DEN. MCCOLLUM ATTORN EY Patented Oct.22,1940 V 2,219,270

1 UNITED- STATES "PAT N OFFICE w 2,219,210"v Y AUTOMATIC oLU'ron ACTUATING Y 2 MECHANISM James H. KQMcCollum and Henry J. De N. McQollum,Evanston,Ill. v I Original application January '17, 19 31, Serial'N o.

509,310. Divided'and thisapplication September25, 1935, Serial No. 42,168 I Y. r

p p 44 Claims, (cries-m) This invention relates generally to automatic closure,-- especially if the throttle control is operclutch-operating mechanism such as is now ated contemporaneously with'the clutch'control. quite'commonly used on motor cars propelled-by Tov overcome this diflic'ulty to. a certain extent gas engines to relieve the cart-driver from dithe connection from pistonto clutchlevenmay 1 5 rectly opening and/or closing the power trans be madeadjustable as to length as shown, de-

mitting clutch during manyperiodsof'car operscribed and claimed in our .said application 5 ation, said mechanism automatically .disengag- Serial No. 509,310. The lengthening of this'pising such clutch whenever the throttleof the gas ton connection from time to time, to the proper engine is closed to'idling position, and permitting extent, will then temporarily compensate, for the clutch to engage when or just before such such previously; occurring. vwear of the clutch 10 throttle is opened. .parts and restore the proper timing of the two- In such mechanism it is-im'portant that the stage-mechanism until further wearfof the parts "clutch-engaging movement of the clutch lever, compels a further readjustment. H y f or other. clutch-actuating element, which usu- ,It is the object of the present invention, howally is normally biased to occupy a clutch closing ever, to provide (in addition to the possible ad- 15 or engaging position, shall-occur intwo stages, justment in length ofpiston rod for initial ini. e., a first stage which will move the clutch elestallation) means for making the twoestage ments proper up toinitial'engagementand shall I mechanism automatically and continuously selfbe as rapid as is conveniently possible, and adjustable as to timing,fso"that itwill, afterinthereafter a second,"slower stage for completion stallation and initial adjustment, automatically of the clutch engagement'-this latter to .,precompensate for clutch wear and always begin vent grabbing of the clutch andsudden. jerkthe second and/or slower stage of its clutch closing of the car;

i ing movement whenever the initial engagement Variousforms-of apparatus for producing such --of,the clutch faces occurs two stage operation'in the automatic closing or In the accompanying drawi which is a copy engaging'of a clutch, are shown and described 1 of 'Fig. 5 of our. prior application Serial No. in our co-pending application Serial No. 509,310, 509,310 (of which this is a division) and is a filed January 1'7; 1931, of which this presentap- V, diagrammatic vertical section of a power-operplication is a division; ated clutch controlling mechanism'with its at- In certain of the several types of apparatus. tachment to certain parts ofia motor car (shown 30 illustrated in our said prior application the. point broken away), there is shown one form of appain the clutch closing movement of the automatic ratus which is designed to operate in accordance apparatus at which the second, or slower, stage. with-the principle of automatic, second-stage of such movement begins is fixed. Thus, if the adjustment lastabove referredto. servo-motor which moves the clutch-actuating Referring to the drawing, theusual clutch 'lever comprises a vacuum cylinderwith a piston pedal of a motor car is shown at 2, a portion of moving therein and operatively connected, to the chassis of which car is shown at 45. This such lever, the second stage of the piston movepedal is mounted on the clutchlever I, which ment may begin when it closes or passes a port is keyed to. the clutch operating shaft I and in the cylinder wa1ls.' For proper operation, such normally held ina clutch engaging position by 40 apparatus must'be so designed that such piston I the, tension ofthe spring 2?. Consequently this will reach that portjust as the slack of the. clutch motor-vehicle clutch has a, normal bias toward mechanism has been taken up "and the initial operative condition with the elements thereof in contact between the' clutch faces occurs. Alengagement witheach others j though, however, a new apparatus mayahave 125 is a section of the intake manifold ofthe 45 been carefully thus adjusted, it is obvious that motor to which the combustible mixture is adafter the clutch faces have been worn down in mitted through] the carburetor '21 having a use, and other additional slack in the operating throttle valve 28 of the usual butterfly'type opparts has similarly resulted, the two-stage erated by the throttle lever 30 and limited in its mechanism proper willhavegotten out'of regisvrnovei'nent by. the adjustable stop mechanism 29 try, and thereafter will begin to check the clutch cooperating with the fixed stop rib 29. I closing movement before any clutch engagement This throttle valve is normally held in nearly has occurred, thus delaying clutch engagement closed or idling position-by the spring 3| anand permitting the motor to race before any load chored at 60. It can be opened by motion of is thrown on it by any partial or completerclutch the accelerator pedal I mounted on rod 39 prothread connection there shown. 48 is a vlocknut.

Throttle rod 38 slides in this sleeve and when the pedal 1 is fully retracted by the action of spring 54, there is a gap left between-the end of 8 The 'powermechanism for operating" the clutch shown in this drawing comprises the vacuum cylinder 8 which is pivotally mounted on the chassis 48 by meansof the pedestal 4'| fastened to the chassis by screw bolts 8|, 5|, and the lu 48 projecting beyond the closed end of the cylinder and hinged or pivoted to the pedestal 41 at 88. I

On the outer end of the piston rod 3 is the screw thread 5 by'means of which it is adjustably connected to the fork 4 which carries the pin 82 in its open end, forming a pivotal connection with the pedal lever I. There is a locknut 8 on the piston rod. I2 is a conduit connected to the left hand end oi cylinder 8 by the port l2 and connected at its other end to a port l8 in the casing l8 of the piston valvev l8.

.The right handend of the cylinder 8 has the skeleton head 4| held'in place by the screws 53, and serving by means of the central perforated boss 88 as a guide for the piston rod 8, the open-. ings 42 in such piston head rendering the right hand end of the cylinder interior open to the atmosphere. The left hand end of the cylinder, on the other side of the piston 18, being connected by port l2 and passageway 2, as before described, to the interior of the valve casing 8, is also (when valve 'II is in the position shown in the drawing) further connected through ports l8, nipple 28, rubber coupling l4 and nipple 28, to the interior of the intake manifold 28. The rubber coupling I4 is inserted to permit the slight movement of the cylinder 8 and the valve connections which occurs about the pivot 88 on account of angularity of the clutch lever'| to'which the piston rod is connected at 82. The valve |5 is of the double piston type having the two full bodied sections 33 and separated by an annular portion of reduced cross section. This valve is pivotally connected at 35 to the accelerator rod 88. This rod is also connected by link 88 to swinging lever 83 having a fixed pivot at 83 on the cylinder 8, and tension spring 84, connected to lever 83 and anchored at 88 on the cylinder 8, 'serves as an accelerator return spring,

, normally biasing the accelerator to occupy the position shown in the draWing With the valve I8 80 located that its said annular portion of reduced diameter is opposite ports |8, thus establishing communication from the left hand end of cylinder 8 to the intake manifold 25.

The right hand pistonportion 84 of'valve I8 is elongated so that after the accelerator I has been started in its movement toward the left to take up the lost motion in the throttle connection and close the ports I! so that suction of the .jecting through footboard 8 and having a pivotal intake manifold is closed off from cylinder 8, the additional considerable movement of the accelerator necessary to give full throttle opening will not reopen ports l8. Consequently such opening only occurs when the operator takes his foot off the, accelerator and spring 84 pulls the parts back into the position shown in the draw- A reducing valve 84 normally biased for closure by spring 8| admits air through ports 84 to conduit l2 and cylinder 9, whenever the pressure differential on it caused by subatmospheric pressures within the latter is enough to further stretch spring 8|.

The operationof the above described apparatus .is as follows:

With the parts in the position shown in the drawing, the clutch is held open by the vacuum in the intake manifold 25 and the throttle is in idling position. If the car is standing still and the operator wishes to start it in motion, he presses the accelerator button 1 ashort distance to the left against the resistance of spring 54,

movement of the piston Hi to the right (under the pull of the clutch springs, conventionally indicated at 2!) allows the clutch lever-l also to begin swinging to the right, and this condition "continues until the reduced tension of the clutch springs produced by the partial clutch closure has caused their tension to equalize with the previously reduced tension of spring 8|, whereupon the valve 84 will close and the parts will stop in the positions then assumed. If,--however, accelerator 1 has been pushed far enough to the left to begin to open the throttle, the tensionon the spring 8| will have been sufilciently further reduced to allow the piston ill to have moved past the leakage port 88 before the above described equalization of tension of springs 2 and 8| will have'occurred, and then,'afterthe closure of the valve 84, the slow intake of air through port 88 will permit the slower second stage of clutch closure movement to occur, although this second stage of clutch movement of course may have its initiation delayed somewhat by an extreme depression of accelerator I which, while opening throttle valve 28 "will haveso reduced tension on spring 8| that valve 84 will 'be free to openand stay open until nearly atmospheric pressurehas been established in the lefthand end of cylinder 8, and so put the clutch insubstantial but not full engagement promptly.

piston l0 under the pull of theclutch closing spring 2' slows down, and when such increase of internal pressure has reduced the remaining excess of pressure of the exterior atmosphere on the outer face of valve 84 to a given extent, spring 8| will thereupon close it. Such slowing down may such movement result from, the diminishing pull of the clutch closing springs as their extent of flexure is reduced in the final stages of the clutch-closing movement (as before described), or may resultv from any sufiicient slowingdown of the speedof the piston movement resulting from other causes, as by the resistance resulting from the initial engagement of the clutch members. The latter occurrence 'will produce a rise of ficient to close valve 84 and a slower, second and final stage of clutch closing action will thenfollow, since air can thereafter enter the cylinder l0 only slowly throughleakage port 58 if piston-i8 has then passed thatport, or by. furth'er 'movement of accelerator to the left. 7

It will therefore beseen that-the servo-motor, comprisingthe vacuum cylinder 9, piston and piston rod 3, with the valve connections described, forms in substance a pressure responsive device connected to the motor ehicle clutchnand operative for moving the clutch elementsoutof engagement with each other. The conduits 28, I4,

20 and I2 constitute a fluid transmitting connec- I5 acts directly to open the suction connection and cause a clutch disengaging operation of theservomotor, it also acts directly to initiate a clutch engaging operation of the servo-motor by closing the vacuum connection and so rendering such operation possible, and acts effectively. (if indirectly) for that purpose by swinging lever 83 to the left toreduce the tension on spring 8| ,so that the full manifold vacuum trapped'imcylinder 9 by the closing movement of valve Hi to the left may open valve 84 and permit air to flow into said cylinder behind piston- Hi. In performing this last mentioned function, valve -|5 acts through the linkage comprising pivot 35, on valve I5, the lefth'and portion of rod 39 and-the link 8317 connecting the latter to lever 83, which lever serves as an adjustable anchorage for spring 8|. Therefore, the movements of primary valve I5 initiate'a clutch engaging operation because if it does not first move'to the left and shut off the manifold-suction, no such clutch engaging operation could occur even if valve 84 were-opened by some other means and also because valve84 cannot open till after valve l5 has moved to the left to reduce the'tension on spring 8|. Unless some means 'for reducing the tension on spring 8| is provided, it will neveropen. It is evident, therefore, that the parts are so constructed'and arranged that with operation of said primary, valve to initiate a clutch engaging operation of the motor, the secondary valve remains operative to' admit atmosphere. to the motorand j effect a relatively rapid engaging movement of the driven clutch element until the driven clutch element is moved into contact with the drivingclutch element, whereupon the secondary valve is automatically operated to in 'municationof-the motor with the atmosphere and thereby effect a retardation inthe clutch engaging movement of the driven clutch element,

pressure sufinitial. opening under action of some if 'ther distance halfway point in its full'movement, at'which the initial clutch, face contact would {usually have occurred, This delayed closure of valve 84 will part close off'the comthereafter" continuing at the greatly reduced speed permitted by inflow of air through leakage having passed it so that it then opens into the vacuum space behind the piston:

Such passage of piston) beyond port 58 would normally occur because the, standard clutch mechanism is so adjusted that thelever swings about half way back from its extreme forwardmo'vemen't, producing a wide open position of the clutch, befor'ei the initial fconta'ct between the port58, which will have been brought into action by reason of the piston ll clutch faces occurs, and furthermore the'degree of slackeningof tension on spring 8| resulting from the closing movement of valve l5 would so reduce the effeetivepull of said spring as to prevent its closingthe valv e 84 (after the'latters the full vacuum in cylinder '8) until the piston .|8 had travelled tothe right beyond the result in part also because an appreciable period of time must has been checked by initial clutch-facecontact before theoriginally low absolute pressure (high vacuum), in ,the cylinder behind thejpiston can be increased by inflowing air to a point that will permit valve 84 to close completely and shut off further inflow of air throughpor'tsj84a. By that time piston ||l usually will certainly have passed leakageport 56, and the slow, minute second stage of clutch closing movement effecting cdmplete absorption of all further resilient yielding of the clutch parts will thereafter be permitted by slow inflow of air through such leakage port 58 while valve 84 remains closed;

'Of course; if the operator pushes the accelerator far to theleft for the purpose of increasing the powerdelivered by the engine so as to producea quick getaway, the tensionon spring 8 I ,will

,be so greatly and so quickly reduced that all the air needed to equalize pressures on the two sides of piston I l) may quickly enter through ports 84a,

andthe second stage, slow motion producing, mechanism will .be thereupon and thereby disabled. r v

The principles of operation of the invention may be'fur'ther explained; as follows:

The cylinder 9; piston I0, piston-rod :1 and valves 5 and, constitute fluid pressure operated power means for disengaging the clutch and controlling-the engagement thereof, and the valve 84 is, automatically operable 'to vary the fluid pressure of said power means to therebydecrease the rate of movement of thedriven clutch mem- ,ber as it moves into engagement with the driving 'member to thereby retard the completion of the clutch engaging operation of said power means. Such variation of the 'fluid'pressure occurs at two or more points during the outward travelof piston ID from the clutch-released position shown in the drawing according to the manipulation of the valve [5. fI'he first variation in the air. pres sure in cylinder 8 occurs when lever 88 hasbeen 1 .swung't'o the left by complete closure of valve l5, ,thereby reducing the tension of spring 8| which allows valve 84 to be opened by the then existin! pressure differential effective on it. If (for example) the full 'rnanifold vacuum trapped in cylinder 8 when valve l5 thus'closes is 8 lbs., and

the reduction, in tension on spring 8|, resulting from a movement of I5 just sufficient-to close ports i8, is libs. multiplied into the effective area in elapse after the motion of the piston square inches of valve 84, the latter will open a given distance and air will begin flowinginto the cylinder through ports 84a at the particular velocity produced by a pressure difi'erential of 8 lbs. Piston Ill then moves to the right at a speed determined in part by the surplus of the pull of the clutch springs (conventionally indicated at 2a) over whatever pressure differential is then effective on the piston, (which latter would approximate the product of 8 lbs. multiplied by the piston area in square inches) and in part by the volume of air perunit of time flowing through the valve opening. These conditions will permit including the maintenance of a vacuum of approximately 8 lbs.in the cylinderuntilthe initial contact of the clutch faces checks said piston movement and consequently reduces the subsequent rate of inflow of air behind it as the pressure there builds up and the pressure-differential on the air flowing in through partly open valve 84 is correspondingly reduced. After such checking of the velocity of inflow of air the gradually reduced inflow will thus gradually but rapidly reduce the vacuum behind the piston until it drops to 4 lbs., at which point valve 84 closes.

This requires a perceptible period of time, even,

if valve 84 were specially designed'to have-the,

Dur-' piston will have passed it just before clutch-face contact was initiated, and valve' 84 began to close. Thereafter piston lflwill, as a 'result of leakage through port 58, move the minute distance necessary to take up the residual elesticity of the partly compressed clutch linings and of the clutch operating levers and linkage. The time required for this final stage of piston movement (valve 84 being then closed) will be determined (of course) by the area of port 58.

The entire period of clutch closing operation of the servo-motor is therefore divided into two stages, a flrst stage of rapid movement, prior to initial clutch-face contact, and a second shorter period of slow movement thereafter, the latter acting to absorb the elasticity of the clutch elements and their pressure producing linkage. This second stage is itself divisible into two substages, the first of which is contemporaneous with the period of time required for closure of valve 84 while the second is coextensive with the afterinflow of air through port 58. relatively rapid movement is automatically terminated when, and only when, initial contact of the clutch faces occur, which is one of the objects of the present invention. In some other forms of two-stage apparatus, in which the point of transition from one stage to the other is fixed by a manual pre-adjustment of the parts, the rapid movement may be terminated some considerable time before clutch contact occurs, if the ,clutch linings have been worn down thin after a period of use.

Analysed in terms of clutch loadings, the cycle of operations may be described as follows: The maximum clutch load is the effective pressure of the clutch springs. The clutch load is'zero when The first stage of then dropped slightly below the pull of the clutch springs, thus permitting them to .pull the piston to the right, and consequently it persists during this first and more rapid stage of clutch closing movement. The moment contact between clutch faces occurs, however, clutch loading begins and must ultimately attain, and remain at, its maximum during road operation of the car.

'Another object of the inventionis to prevent 1 "would mean clutch grabbing" and a jerking of the car. "The present invention automatically checksthat increase of loading when any predetermined desired amount hasbeen attained and practically immediately after clutch-face contact. This is because at the moment of contact 'the vacuum behind the piston begins to drop rapidly, which means that the absolute air pressure on the pistons rear side begins to rise, and consequently the pressure differential on the piston begins to fall more and more below the pull of the clutch springs, the difference between these two being absorbed as it develops by the in creasing resistance to further compression of the slightly elastic clutch faces. This means that the clutch loading, starting at zero,.goes up rapidly after initial contact of the clutch elements, which is merely another way of saying that the pressure of one clutch element on the other is increasedyas-that is what is meant by loading.

- This clutch loading therefore increases directly through port 56, and the piston stops moving, be-

ing held in position then reached by equalization of the air pressure differential exerted on its outer face, and the net pull of the total clutch spring pressure over the clutch loading then attained. Consequently valve: 84 is automatically'operable in response to variation in the fluid. ressure of the power means to decrease the rate of engagement of the clutch. Also, said valve and its spring 8| constitute means automatically operable at or above a given loading of the clutch members (determined by the tension of spring 8| and adjust- .able by movement of lever 88) to decrease the rate of movement of the driven clutch member (meaningthat member which is driven by the other after clutch closure) as it moves into engagement with the driving member. And it is so operable to thereby retard the completion of the clutch engaging operation of the power means (servo-motor 9,10) andreduce said clutch engaging operation to the particular slower rate of movement permitted by inflow of air through leakage port 58.

If, after the first, almost instantaneous increase 'of clutch loading has been attained, as above described, valve I5 is moved one or more times a little further to the left by successive further depressions of accelerator 1, one or more additional rapid increases of clutch loading (say to 5, 6 and 7 lbs. per unit of piston area) may be produced, and thereafter the final slower rise to maximum clutch loading occurs as the result of slow leakage of air through port'88, as before.

Means other than those hercinshown. and

above described might be substituted and 'operthus rendering the initiation of the slower, second stage of clutch-closing movement automatically self-adjusting to suit varying conditions of wearing down of the clutch elements, and such. would still be within the scope of our invention as.

hereinafter defined in certain of the broader appended claims. z vHaving described our invention,- we claim:

1., In a pneumatic apparatus for actuating a movable. 'member of a mechanism adapted to operate the power transmission. clutch: of a ,motor car, comprising. a cylinderqopento the atmos+ phere atone end and connected-totheintake manifoldofthe motor at the other, a manually operablevalve. insaid connection, .a piston-in said cylinder connected to said clutch operating. member; and a. spring normally tending to produce 'aclutch engaging movement: of:said member, whereby, when said val-vein the, intake 'man-- ifold connection is opened said member. will be .pul'led into a clutch disengaging position, the

combination, with said above described apparatus, of automatic means adapted-to producea relatively rapid clutch engaging 'movement' of said movable member followed :by'a slower movement for completion of the 'engagement'comp'ris ing apoppet valve adapted to open and admit air to that end of said cylinder-which is'connected to said manifold, aspring normally tend-- ing to hold said valve closed and having'a degree of tension sufficient to hold it closed during-the latter portion of the travel ofsaid movable member which produces clutch engagement while said clutch closing 'spring is partially expanded, but permitting said valve to open while-the piston is subjected to the pull ofiully compressed clutch springs at the beginning of its outward move-' ment, and automatic means for holding, said valve closed during the clutch disengaging movement of said piston andmovable. member co' n nected thereto. 2 An apparatusesuch combined with meansfor slowly admitting a' sep-" arate supply of air to said cylinder duringsaid latter 'portion' of the travel jof said. 'rriovable] as definedf in claim, 1

member.

3'."In a pneumatically operated clutch actuat ing apparatus comprising a movable clutchxcon-L trollingmember, a spring tendingftomove said m'e'mber in a direction to. close the clutch and a I pneumatic ,motor device tending I to move said; member in a clutch opening directionwhen air is exhausted therefrom, the combination. with said above descrhbedlapparatus of, a valve controlling the admission of air to the interior lof said pneumatic device'jand means for automatical-ly elosing said valve whenever "the. subatmosphe'ric pressure in said motor device rises to a certain amount. 1

'4. In an automotive'vehicle provided'with clutch-actuating member; powermeans for operating said clutch-actuating"member including a pneumatic motor and valvemechanism "for" controlling the operation of said clutch-operating motor, said valve mechanism'comprising means for initiating the" clutch disengaging and engag-, ing operations "ofsaid motor, and'further' co prisingmeans operable in accordance with -the degree of vacuum within one end'of said motor 1 to abruptly reduce the; rate of movement of the ther comprising means operable. by. and in actions to permitmovernentofjsaid valve-member aforementioned clutch actuating member as the. clutchis-being engaged. v

5 In an automotive vehicle provided witha clutchvcontrolling member, pressure differential operated means for operating said clutch-con- 5 cordance with the vacuumjcreated within the motor, asthe clutch is being'engaged to abruptly ,modiiy the rate of change-of prwsure-difierential acting on the aforementionedreciprocable power elementto thereby abruptly decrease the rate of engaging, movement of the clutch.

. 6. The combination witnan' automotive vehicle. provided withan internal combustion engineand a clutch controlling member, otvacuum-operated power means-for operating isaid member, said powermeans'includingga vacuum actuated motor having a chamber containing a reciprocable' ele.-- ment operatively, connected withsaid member, a conduitinterconnecting one end of said chamberwith-the intake manifold oisaid engine, valvular mechanism for controlling theflow-of air to and from said chamber; said valvular mechanism comprising means for initiating the clutch disengaging and engaging operations of "said motor by alternately openingand closing .the-connection between said manifold and said chamber, and furthercomprising a valve member operable to admit air from the atmosphere to thchamber interior after the" aforementioned means has been operated to initiate" the" engagement of the clutch, together with 'yieldablemeans acting; on saidvalve member, said valve-member being subjected to a pressure-differential created by the pressure of the atmosphere acting on one side thereof and the partial vacuum in sali d'jmotor chamber acting on the other sidefsaid pressure difierential acting m" opposition fto the force of saidyieldable means, whereby, when the degree of vacuumfwi-thin said chamberis decreasedato a predetermineddegree, said'yieldabl'emeans ru eto cut off the then einsting communication between the atmosphere and said cnamberaround said valve memberli 3 apparatus in claim-v combined with means for slowly admitting addimem ber'has shut off thexinitial admission oiFair theretg; it" l 8. In an automobileequipped with an internal combustionfengine for propelling it',;a pedalfor controlling said engine, a clutch-actiiatingmember normally biased toward clutch-closing position, "and a vacuum-actuated fservo motor for moving said; member 'to clutch-opening position .together with afmanuall'y operable valve adapted;

to open "and close a 'vacuum connection" to said j servo-motor, the combination} with "said above";

described apparatus, a; means Toperable in response to-p'ressure 'variation'in the servo-motor for automatically controlling the clutch-closing" movements of said motorcomprlsing a reducing valve normally biased by yielding means toward" closed position and adapted'to admit automatically regulated volumes of air to the vacuum 7 ref at a.

tional air to saidsmotorchamber aftersaid-valve space in said servo-motor after said vacuum connection has been closed.

9. Means such as defined in claim 8 combined with mechanism forautomatically admitting an additional small volume of air to said vacuum space during the latter portion of the clutchclosing movement of said clutch-actuating member.

10. Means such as defined in claim 8 combined with a manually operable device for modifying the action of said reducing valve while the clutch-closing operation is going on.

11. Means such as defined in claim 8 combined with a manually operable device for modifying the action of said reducing valve while the clutchclosing operation is going on simultaneously and correspondingly with the movement of said'engine controlling pedal.

12. Means such as defined in claim 8 which comprise a connection from said reducing valve to said engine-controlling pedal operative to cause said reducing valve to admit increasing volumes of air tosaid vacuum space as the power delivered by the engine is increased.

13. Means such as defined in claim 8 comprising a tension spring connected to said valve at one end and to a lever at theother, and an operative connection from said lever to said enginecontrolling pedal such that as the latter is moved to increase the power beingdelivered by the engine it will'so swing said lever as to decrease the tension on said spring.

. 14. A combination such as defined in claim 8 in which said manually controllable connection from the intake manifold comprises a valve so connected to said engine controlling pedal. as to be closed during substantially the entire period of engine-controlling movements of the latter.

15. In avacuum power clutch mechanism, for a motor car having a clutch operating member, an intake manifold, a carburetor, throttle valve and throttle arm having a return spring, and a throttle rod having adjustable lost motion, the combination, with. said above described mechanism of two valve casings and valves .therein, an accelerator, one of said valves being positively attached to said accelerator and said accelerator being operatively connected to said throttlerod, a cylinder having a small leakage port in its wall and mounted on the car frame, a lever mounted on a fixed pivot and operatively connected to said accelerator, a spring tending to retract said accelerator, a spring connecting said lever and the other valve, conduits, controlled by said valves, connecting said cylinder to said intake manifold and to the atmosphere, a piston in said cylinder, provided with a piston rod of adjustable length operatively connected to said clutch operating member, said parts cooperating substantially as described. l l v i 16. Ina pneumatic apparatusfor actuating a movable member of a mechanism adapted to operate the power transmission clutch of a'motor car, comprising acylinder open to the atmosphere at one end and connected to the intake manifold of the motor at the other, a manually operable valve in said connection, a pistonin said cylinder connected to said clutch operating member, and a spring normally tending to produce a clutch engaging'movement of said member, whereby, when said valve. in the intake manifold connection is opened said member will be pulled into a clutch disengaging position, the'combination, with said above described apparatus, of automatic means adapted to produce a relatively rapidclutch engaging movement of said movable member followed by a slower movement for completion of the engagement comprising a poppet valve in said intake manifold connection opening inwardly to admit air thereto, a spring normally-tending to hold said valve closed and mechanism connecting said spring and said manually operable valve adapted to cause any closing movement of said valve to diminish to a proportionate extent the movement in the clutch engaging operation is thereby to that extent permitted.

18. A'combinationsuch as defined in claim 16 in which said cylinder is provided with a leakage port in its wall at a point such that said piston will have passed 'it before its clutch movement is completed.

19. In an automotive vehicle provided with an internal combustion engine and a clutch actuating member, pressure differential operated means for operating said clutch actuating member, a motor operably connected to the clutch, a fluid transmitting connectioninterconnecting one end of said motorwith the engine, and valve means for controlling the fiow of power fiuid to and from said motor,- said valve means comprising means operable to alternately open and close the fluid transmitting connection to initiate the clutch disengaging and engaging operations of said motor, and further comprising other means operative to permit an infiux of power fluid into said motor to effect a relatively rapid firststage of engaging movement of, the clutch, and further operative to automatically appreciably reduce the rate of influx of power fluid to said motor when the friction elements of the clutch contact one with the other. i

20. In an automotive vehicle provided with an internal-combustion engine and 'a clutch actuating 'member, pressure differential operated means for operating said clutch actuating member, a motor operably connected to the clutch, a,

fluid transmitting connection interconnecting one end of said motor with the engine, and valve means for controlling the flow of power fluid to and from said moton'said valve means comprising manually operated means operable .to alternately open and close the fluid transmitting connection to initiate the clutch disengaging and engaging operations of said motor, and further comprising other means operative to permit an influx of power fluid into said motor to effect a rela- -tively rapid first stage of engaging movement of the clutch, and further operative toautomatic-ally appreciably reduce the rate of influx ofpower fluid to said motor when the friction elements of the clutch contact one with the other, said valve means further comprising means for effecting a relatively slow engaging movement of the clutch engaging.

after the termination of the aforementioned rapid first stage of movement. a

21..In an automotive vehicle provided with a clutch actuating member, power means for operating said clutch actuating member, including a motor and valve means for controlling the operation of said clutch operating motor, said valve means comprising means for initiating the clutch accordance with the degree of vacuum within one end of said motor to abruptly reduce the rate of movement of the aforementioned clutch actuat ing member as the clutch is being engaged.

22. In an automotive vehicle provided with a I clutch, pressure differential operated means for operating said clutch comprising a fluid motor including a reciprocable power element operably connected to the clutch, and further-comprising valvular means for controlling the gaseous pressure with said motor, said valvular means comprising manually operated means for initiat-i ing the clutch disengaging and engagingoperations of said motor, and further comprising means operable by and in accordance with the vacuum created within the motoras the clutch is being'engaged to abruptly change the rate of change of pressurev differential acting on the aforementioned reciprocable powerelement to thereby abruptly decrease the rate of engaging movement of the clutch.

23. In an automotive vehicle provided with an internal-combustion engine and a clutch, vacuum operated power means for operating said clutch, said power means including a motor having a reciprocable element operatively connected with the .clutch, a fluid transmitting-connection interconnecting one end of said motor with the intake manifold of said engine, and valvular means for controlling the mode of flowof air to and from said motor, said valvular means comprising means for initiating the clutch disen'gag ing and engaging operations of said'motor by alternately opening and closing the connection between the manifold and motor, said valvular means further comprising a reciprocablevalve member operable to admit atmosphere to the motor after the aforementioned means is operated to initiate the engagement of the clutch, yieldable means acting on said latter member, said reciprocable valve member being subjected to a pressure differential created by the effect of the atmosphere acting on one side of said member and the vacuum of said motor acting on the other side of said engine, said differential acting in pposition to the force of said yieldable means whereby when the degree of vacuum within said motor is decreased to a predetermined factor said yieldable means functions to move said reciprocable valve member to' cut off the then existing communication between the atmosphere and motor via said reciprocable valve member.

24. In an automotive vehicle provided with an internal-combustion engine and a clutch, vacuum operated power means for operating said clutch, said power means including a motor having a reciprocable element operatively connected with a clutch, a fluid transmitting connection interconnecting one end of said motor with the intake manifold of said engine, and valvular means for controlling the mode of flow of air to andfrom said motor, said valvular means comprising means for initiating the clutch disengaging and engaging operations of said motor by alternately opening and closing the connection between the manifold and motor, said valvular means further comprising a reciprocable valve member operable to admit atmosphere to the motor'after the aforementioned means is operated to initiate the engagement of the clutch, yieldable means acting on said latter member, said reciprocable valve member being subjectedto a pressure differential created by the effect of the atmosphere acting on one side of said member and the vacuum of said motor acting on the other side of said engine, said differential actingin opposition to I the force of said yieldable means whereby when the degree of vacuum within said motor is decreased to a predetermined factor said yieldable means functions tomove said reciprocable valve member to cut off the then existing communica-- tion between the atmosphere and motor via said reciprocable valve member, said valvular means further comprising means operable after said aforementioned reciprocable valve means has cut I off the connection between the atmosphere and motor to admit an additional amount of atmosphere into the motor. I I

"25. Apparatus of the character described comprising a pressure responsivedevice connected to a motor vehicle clutch and operative forv moving the clutch elements out of engagement witheach other, means for supplying vacuum to said pressure responsive device to render it operative, means for at least partially releasing the vacuum actingon said pressure responsive device to release the clutch elements for movement toward operative engagement with each other, means operative upon initial contact of the clutch elements with eachother-for checking the motion of the clutch elements toward operative engagement, and means for releasing the clutch elements'for movement into operative engagement after their movement has been checked by said last named means. I v

26. Apparatus of the character described comprising a pressure responsive device connected to a motor vehicle clutch, a conduit connected to a source of'suction and to said device and operative for connecting said device to the source of suction to move the clutchelements out of engagement with each other, means operative upon the admission of atmospheric pressure to said conduit to release the clutch elements for movement toward operative engagement, said pressure responsive device operating to maintain a partial vacuum in said conduit during movement of the clutch "plates toward operative engagement. means actuated by a drop in vacuum in said conduit occurringupon initial contact of the clutch elements for checking movement of the clutch elements toward operative engagement, and means for releasing the clutch elements for movement into operative engagement after their movement has been checked by said last named means.

27. Apparatus of the character described comprising a pressure responsive device connected to a motor vehicle clutch, a conduit connected to a source of suction and to said device and operative for connecting said device to the source of suction to move the clutch elements out of engagement with each other, means operative upon the admission of atmospheric pressure to said con duit to release the clutch elements for movement' toward operative engagement, said pressure responsive device operating to maintain a partial vacuum in said conduit during movement of the clutch elements toward operative engagement, an elastically actuated valve operable to closed position by a drop in vacuum in said passage occurring upon initial contact of the clutch elements for checking movement of the clutch elements toward operative engagement, and means for releasing the clutch elements for movement into operative engagement after their movement has been checked by said last named means.

28. The combination with a motor vehicle ments with each other for checking the motion of the clutch elements toward operative engagement, and means for releasing the clutch elements for movement into operative engagement after their movement has been checked by said last named means. 7

29. The combination with a motor vehicle clutch having a normal bias to operative condition with the elements thereof in engagement with'each other, of a pressure responsive device connected to an operating member of the clutch,

a conduit connected to a source of suction and to said device and operative for connecting said device to the source of suction to move the clutch elements out, of engagement with each other, means operative upon the admission of atmospheric pressure to said conduit to release the clutch elements for movement, toward operative engagement, said pressure responsive device operating to maintain a partial vacuum in said conduit during movement of the clutchplates toward operative engagement, means actuated by a drop in vacuum in said conduit occurring upon initial contact of the clutch elements for checking movement of the clutch elements toward each other, and means for releasing the clutch elements for movement into operative engagement after their movement has been checked by said last named means.

30. The combination with a motor vehicle clutch having a normal bias to operative condition with the elements thereof in engagement with each other, of a conduit connected to a source of suction and to said device and operative for connecting said device to the source of suction to move the clutch elements out of engagement with each other, means operative upon the admission of atmospheric pressure to said conduit to release the clutch elements for movement toward operative engagement, said pressure responsive device operating to maintain a partial vacuum in said conduit during movement of the clutch elements toward operative engagement, an elastically actuated valve operable to closed position by a drop in vacuum in said passage occurring upon initial contact of the clutch elements for checking movement of the clutch elements toward operative engagement, and means for releasing the clutch elements fonmovement into operative engagement after their movement has been checked by said last named means.

31. In a pneumatic apparatus for actuating a movable member of a mechanism adapted to operate the power transmission clutch of a motor car, comprising a cylinder open to the atmosphere at one end and connected to the intake manifold' clutch engaging movement of said member,

whereby, when said valve in the intake manifold connection is opened said member will be pulled into a clutch disengaging position, the combination, with said above described apparatus, of automatic means adapted to produce a relatively rapid clutch engaging movement of said movable member followed by a slower movement for completion of the engagement comprising a valve adapted to open'and admit air to that end of said cylinder which is connected to said manifold, a spring normally tending to hold said valve closed and having a degree of tension suflicient to hold it closed during the latter portion of the travel of said movable member which produces clutch engagement whilethe force of said clutch closing spring is partially reduced, but permitting said valve to open while the piston is subjected to the pull of the full force of said clutch springs at the beginning of its outward movement, and automatic means for holding said valve closed during the clutch disengaging movement of said piston and movable member connected thereto.

32. An 'apparatus'such as defined in claim 31 combined with means for slowly admitting a separate supply of air to said cylinder during said latter portion of the travel. of said movable member. g

33. In an automotive vehicle provided with a clutch-actuating member, power means for operating said clutch actuatingmember including a pneumatic motor and valve mechanism for controlling the operation of said clutch operating motor, said valve mechanism comprising means for initiating the clutch disengaging and engaging operations of said motor, and further comprising means operable in acordance with the degree of vacuum within one. end of the air chamber of said motor to abruptly reduce the rate of movement of the aforementioned clutch-actuating member as the clutch is being engaged.

34. In an automotive vehicle provided with a clutch comprising driving and driven members,

fluid pressure operated power means for disengaging the clutch and controlling the engagement thereof, said power means comprising a valve automatically operable, when the driving and driven members of the clutch contact one with another, to vary the fluid pressure of said power means to thereby decrease the rate of engagement of the clutch.

35. In combination with a power actuated automotive clutch having driving and driven members, power means for disengaging, said clutch members and controlling the engagement thereof, said power means comprising means, automatically operable when the clutch members contact and automatically compensating for wearof said membe'rs,-to decrease the rate of movement of the driven clutch member as it moves into engagement with the driving member to thereby retard the completion of the clutch engaging operation of said power means.

36. In an automotive vehicle provided with an internal-combustion engine and a clutch actuating member, pressure differential operated means for operating said clutch actuating member comprising a motor operably connected to the clutch, a fluid transmitting connection interconnecting one end of said motor with the engine, and valve means for controlling the flow of power fluid to and fromsaid motor, said valve means comprising means operable to alternately open and close the fluid transmitting connection to initiate the clutch engaging and disengaging operations of saidmotor, and further comprising other means operative to so control the presmotor operably connected with the sure of the power fluid within said motor as to effect a relatively rapid first stage of engaging movement of the clutch, and further operative to automatically appreciably change the pressure of the power fluid within said motor when the friction elements of the clutch contact one with the other,

3'7. Clutch control mechanism for an automotive vehicle provided with a clutch having driving and driven elements and comprising in combination therewith, a pressure differential operated mary control valve operative to initiate the disengaging and engaging operations of said motor and a pressure differential operated valve, operable when the clutch elements initially contact, to automatically vary the rate of clutch engagement.

38. In an automotive vehicle provided with a clutch having driving and driven elements, power means for operating said clutch comprising a pressure differential operated motor operably connected to the driven element of the clutch, a control valve for initiating the clutch disengaging and engaging operations of said motor, and other valve means for controlling the clutch engaging operation of the motor comprising means controlled by a spring, the atmosphere and the fluid pressure of the motor and automatically operative, when the elements of the clutch initially contact, to retard the engagement of the clutch.

39. In an automotive vehicle provided, with an intake manifold and a clutch having driving and driven elements, a pressure difierential operated motor operably connected with the driven element of the clutch, a fluid transmitting connection interconnecting said manifold and motor, a primary valve incorporated in said connection, a secondary valve, means for controlling the clutch engaging operation of the motor, yieldable means acting on said latter valve, means for connecting said secondary valve means with the atmosphere, and fluid transmitting means inter,-

clutch, a priv trolling the admission of air to the interior or said pneumatic device and means for automatically closing said valve whenever the subatmospheric pressure in said motor device rises to a certain amount, said pneumatic motor device having another means for admitting air to its interior in very small volume; whereby after said automatically controlled valve has been closed, 1

air may still be admitted to the interior of said pneumatic device, but much more slowly, the original speed of clutch closing being thereby correspondingly slowed down.

41. In a mechanism for operating the clutch of an automotive vehicle, the combination of a pressure-dlfierential operated motor, valve means for controlling the clutch-disengaging operations of said motor, and automatic means for so controlling the clutch-engaging operation of the motor as to sharply check further increase of pressure between the clutch surfaces whenever relatively close contact between the driving and driven elements of the clutch has occurred; whereby any period of rapid, substantially free movement of one of said elements toward the other occurring in any clutch-closing cycle is automatically terminated at the moment of such contact, however much the contact surfaces may have been worn down by use or built up by lining renewals or other adjustments.

42. In an automatic clutch-actuating apparatus, the combination of a fluid-containing receptacle, an element adapted to be moved by variations of fluid pressure in said receptacle, an operative connection from said element to a clutch-actuating member, and a valve controlling passage of air between the exterior atmosphere and the interior of said receptacle which is auto- "matically operable whenever the pressure diflerconnecting said secondary valve with the motor,

said parts being so constructed and arranged that with operation of said primary valve to initiate a clutch engaging operation of the motor, the secondary valve remains operative to admit atmosphere to the motor and eifect a relatively rapid engaging movement of the driven clutch element until the driven clutch element is moved into contact with the driving clutch element, whereupon the secondary valve is automatically operated to in part close off the communication of the motor with the atmosphere and thereby effect a retardation in the clutch engaging movement of the driven clutch element.

40. In a pneumatically operated clutch actuating apparatus comprising a movable clutch controlling member, a spring tending to move said member in and a pneumatic motor device tending to move said member in a clutch opening direction when air is exhausted therefrom, the combination with said above described. apparatus of a valve con a direction to close the clutch ential on said element is varied to a predetermined extent.

43. In an automatic clutch-actuating apparatus, the combination of a servo-motor operable by variations of air pressures therein, a motiontransmitting connection from said servo-motor to a clutch-actuating member, and automatic means for substantially checking any clutchclosing operation of servo-motor whenever the pressure of air then existing in a chamber therein rises a predetermined amount per unit of area of the interior surface of said chamber exposed to such pressure.

44. In an automatic clutch-actuating apparatusf'the combination of a fluid-containing receptacle, an element adapted to be moved by variations of fluid pressure in said receptacle, an

operative connection from said element to a clutch-actuating member, and a valve controlling passage of air between the exterior atmosphere and the interior of said receptacle which is automatically operable whenever the pressure difierential on said element mined amount.

JAMES H. K. MccoLLUM.

J.- DE N, M COILUM.

is reduced to a predeter 

